Examining the structure of recent doors for a refrigerator, outer surface is all in a 2 dimensional flat surface shape, and filled with foamed heat insulation materials. Structures of doors for a refrigerator are presented in prior publications such as Korea laid-open patent 10-2002-0019170.
Outer surfaces of these structures of doors for a refrigerator are in a shape of a 2 dimensional flat surface and finishing work is done with glass materials. However, normal a refrigerator with 2 dimensional flat surface shaped outer surface doors lack realization of 3 dimensional shapes. To overcome this disadvantage, attempts to have 3 dimensional shapes for the door are active, but there are problems in difficulty in manufacturing with common technologies that use glass finishing materials, and also there are problems of requiring high costs.
And also, even when manufacturing a door for a refrigerator having 3 dimensional shapes, there are problems of what method to use to obtain heat insulation properties.